Set gasLimit and gasPrice on contract transactions

[fmsouza]

I've been searching in the online documentation for a way to set my gasPrice and gasLimit when creating a transaction on a contract, but couldn't find a way to make it work. I attempted to modify the transaction while signing using a CustomSigner, but didn't had any success.

Is there any way to do it?

[ricmoo]

Good point! I need to update the documentation to include details on this.

Any contract operation can take in one additional (optional) parameter, which is an object of overrides.

function foo(address addr) { ... }
function bar(address addr) constant returns (string result) { ... }

can be called with:

// You can optionally override the following on non-constant functions; anything
// you do not override will be determined automatically
var options = { gasPrice: 1000000000, gasLimit: 85000, nonce: 45, value: 0 };
var fooPromise = contract.foo(address, options);

// You can optionally override the following on constant functions
var options = { from: otherAddress };
var barPromise = contract.bar(address, options);

[fmsouza]

Thanks!

[ricmoo]

I've added a small example on the contract non-constant function documentation, but in the documentation overhaul, this will need to have it's own section.

Thanks!

[aakilfernandes]

Looks like you can also override the getGasPrice function of the provider

ethers.js/src.ts/utils/transaction.ts

Lines 224 to 226 in c2ce59f

	if (tx.gasPrice == null) {
	tx.gasPrice = provider.getGasPrice();
	}

[aakilfernandes]

class FastProvider extends ethers.providers.InfuraProvider {
  async getGasPrice() {
    const gasPrice = await super.getGasPrice()
    return gasPrice.add(gasPrice.div(5))
  }
}

careful while doing math with ether's BigNumber. It can't handle decimals

[williamoc74]

Hi, where do I need to add the above in my code to get this to work?
I've added
class FastProvider extends ethers.providers.InfuraProvider {
async getGasPrice() {
const gasPrice = await super.getGasPrice()
return gasPrice.add(gasPrice.div(5))
}
}

but I'm still getting an error
(node:7820) UnhandledPromiseRejectionWarning: Error: cannot estimate gas; transaction may fail or may require manual gas limit (error={"reason":"cannot estimate gas; transaction may fail or may require manual gas limit","code":"UNPREDICTABLE_GAS_LIMIT","error":{"code":3,"response":"{"jsonrpc":"2.0","id":6,"error":{"code":3,"data":

Can anyone guide me in the right direction?

Thanks

[zemse]

Hey @williamoc74, if you just want to add a custom gas price and gas limit to your contract transaction:

await contract.yourMethod(arg1, arg2, {gasPrice: ethers.utils.parseUnits('100', 'gwei'), gasLimit: 1000000});

You can also see docs.

The code from aakilfernandes that you are copying is for using 5 times the existing default gas price as the new default price.

[williamoc74]

Hi @zemse Thank you for the reply.
I'm not to bothered about adding a custom gas price, I just want the contract to run.
I've added the above code but once I add it, it doesn't error, it just runs but doesn't execute anything.

I see you said this else where
The revert is likely because if insufficient msg.value sent to the multisender contract, which tries to send given eth to your target addresses.

const transactionOptions = {
    gasLimit: 6000000,
    gasPrice: ethers.utils.parseUnits('1.0', 'gwei')
    value: ethers.utils.parseEther('3.0') // adding this should fix
}

So I'm going to try this next. If this doesn't work, can I post my code and hopefully we can find a solution that way?
Again, much thanks.. :)

[williamoc74]

No joy with the above - I even remove the "value...."
and its just the same error as I always get

`New pair detected
=================
token0: 0xb28aba015db622386914adFc505A9583ae588829
token1: 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2
pairAddress: 0xaBe41D7Da13649b1BEFE1F487363eCB069CA4E35

Buying new token
=================


tokenIn: 10000000000000000 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2 (WETH)
tokenOut: 386907351979022469 0xb28aba015db622386914adFc505A9583ae588829

(node:6337) UnhandledPromiseRejectionWarning: Error: cannot estimate gas; transaction may fail or may require manual gas limit (error={"reason":"cannot estimate gas; transaction may fail or may require manual gas limit","code":"UNPREDICTABLE_GAS_LIMIT","error":{"code":3,"response":"{"jsonrpc":"2.0","id":6,"error":{"code":3,"data":`

[ricmoo]

Can you include the full error and your current code? If you are passing gasLimit in, you should not be able to get that error… :s

[williamoc74]

Hi Ricmoo..

This is the code

const ethers = require('ethers');

const addresses = {
  WETH: '0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2',
  factory: '0x5C69bEe701ef814a2B6a3EDD4B1652CB9cc5aA6f', 
  router: '0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D',
  recipient: '*****'
}

const mnemonic = '*****';

const provider = new ethers.providers.WebSocketProvider('*****');
const wallet = ethers.Wallet.fromMnemonic(mnemonic);
const account = wallet.connect(provider);
const factory = new ethers.Contract(
  addresses.factory,
  ['event PairCreated(address indexed token0, address indexed token1, address pair, uint)'],
  account
);
const router = new ethers.Contract(
  addresses.router,
  [
    'function getAmountsOut(uint amountIn, address[] memory path) public view returns (uint[] memory amounts)',
    'function swapExactTokensForTokens(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline) external returns (uint[] memory amounts)'
  ],
  account
);

factory.on('PairCreated', async (token0, token1, pairAddress) => {
  console.log(`
    New pair detected
    =================
    token0: ${token0}
    token1: ${token1}
    pairAddress: ${pairAddress}
  `);

  //The quote currency needs to be WETH (we will pay with WETH)
  let tokenIn, tokenOut;
  if(token0 === addresses.WETH) {
    tokenIn = token0; 
    tokenOut = token1;
  }

  if(token1 == addresses.WETH) {
    tokenIn = token1; 
    tokenOut = token0;
  }

  //The quote currency is not WETH
  if(typeof tokenIn === 'undefined') {
    return;
  }

  //We buy for 0.1 ETH of the new token
  const amountIn = ethers.utils.parseUnits('0.01', 'ether');
  const amounts = await router.getAmountsOut(amountIn, [tokenIn, tokenOut]);
  //Our execution price will be a bit different, we need some flexbility
  const amountOutMin = amounts[1].sub(amounts[1].div(10));
  console.log(`
    Buying new token
    =================
    tokenIn: ${amountIn.toString()} ${tokenIn} (WETH)
    tokenOut: ${amountOutMin.toString()} ${tokenOut}
  `);
  const tx = await router.swapExactTokensForTokens(
    amountIn,
    amountOutMin,
    [tokenIn, tokenOut],
    addresses.recipient,
    Date.now() + 1000 * 60 * 10 //10 minutes
  );
  const receipt = await tx.wait(); 
  console.log('Transaction receipt');
  console.log(receipt);
});

I've removed all the code if tried to get it to work
and this is the original error

`New pair detected
=================
token0: 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2
token1: 0xCa5574f9064E9fA5BFe638466Fe61cD0e265AFd4
pairAddress: 0x7a80dF864Ac54d0bCFf9AF3ee758fFf683Dbd681

Buying new token
=================
tokenIn: 20000000000000000 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2 (WETH)
tokenOut: 340267027755796295 0xCa5574f9064E9fA5BFe638466Fe61cD0e265AFd4

(node:11176) UnhandledPromiseRejectionWarning: Error: cannot estimate gas; transaction may fail or may require manual gas limit (error={"reason":"cannot estimate gas; transaction may fail or may require manual gas limit","code":"UNPREDICTABLE_GAS_LIMIT","error":{"code":3,"response":"{"jsonrpc":"2.0","id":10,"error":{"code":3,"data":"0x08c379a0000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000245472616e7366657248656c7065723a205452414e534645525f46524f4d5f4641494c454400000000000000000000000000000000000000000000000000000000","message":"execution reverted: TransferHelper: TRANSFER_FROM_FAILED"}}"},"method":"estimateGas","transaction":{"from":"0x6657acbCF04775b8D36Ca0659F08F281f635F538","gasPrice":{"type":"BigNumber","hex":"0x10ff239a00"},"to":"0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D","data":"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","accessList":null}}, tx={"data":"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","to":{},"from":"0x6657acbCF04775b8D36Ca0659F08F281f635F538","gasPrice":{},"nonce":{},"gasLimit":{},"chainId":{}}, code=UNPREDICTABLE_GAS_LIMIT, version=abstract-signer/5.1.0)
at Logger.makeError (C:\Users\TEST MM\Desktop\unibot\node_modules@ethersproject\logger\lib\index.js:180:21)
at Logger.throwError (C:\Users\TEST MM\Desktop\unibot\node_modules@ethersproject\logger\lib\index.js:189:20)
at C:\Users\TEST MM\Desktop\unibot\node_modules@ethersproject\abstract-signer\lib\index.js:263:47
at processTicksAndRejections (internal/process/task_queues.js:95:5)
at async Promise.all (index 5)
(node:11176) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag --unhandled-rejections=strict (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 2)`

Thanks in advance, I appreciate you taking the time.. :)

[ricmoo]

You still need to pass the overrides (with gasLimit) into the transaction method to const tx = await router.swapExactTokensForTokens(...) that @zemse recommended above.

[williamoc74]

OK, I've tried what I think you mean(I am a noob here, and I realise this isn't a tutorial type forum for noobs so I do appreciate both of you helping me figure this out :) )
but I'm getting another error. The syntax seems correct but it seems as tho I'm just not putting the code in the correct location and the error is with how the function is called.

This is the changed code
//We buy for 0.1 ETH of the new token const amountIn = ethers.utils.parseUnits('0.01', 'ether'); const amounts = await router.getAmountsOut(amountIn, [tokenIn, tokenOut]); //Our execution price will be a bit different, we need some flexbility const amountOutMin = amounts[1].sub(amounts[1].div(10)); console.log(
Buying new token
=================
tokenIn: ${amountIn.toString()} ${tokenIn} (WETH)
tokenOut: ${amountOutMin.toString()} ${tokenOut}
`);
const tx = await router.swapExactTokensForTokens(
await contract.yourMethod(arg1, arg2, {gasPrice: ethers.utils.parseUnits('100', 'gwei'), gasLimit: 1000000});

amountIn,
amountOutMin,
[tokenIn, tokenOut],
addresses.recipient,
Date.now() + 1000 * 60 * 10 //10 minutes

);
const receipt = await tx.wait();
console.log('Transaction receipt');
console.log(receipt);
});`

and this is a screenshot of the error, the last error I posted looked kind of messy so hopefully a screenshot is better.

Thanks again